Crews close the road after a multiple vehicles get into trouble at Centre Street North between Stoney Trail and Highway 566. (Submitted by Rodney Gallant)

Traffic was slowly moving on reopened highways and power returning to homes in southern Alberta after an overnight snowstorm.

Late Thursday afternoon, Environment Canada downgraded the area's winter storm warning to a wind warning with gusts up to 90 km/h, diminishing overnight. More snow — between 10 to 15 centimetres — was forecast over the Cypress Hills and in eastern sections of the Lethbridge region.

Up to 12 centimetres of snow fell on Wednesday night into Thursday morning in Calgary and surrounding areas, causing problems on major highways.

The southbound lanes of Highway 2 reopened between Carstairs and Airdrie on late Thursday afternoon, but major delays were still expected for several hours.

Emergency and highway crews worked on removing vehicles from earlier crashes and packed snow from the driving lanes, said the RCMP. They advised motorists to use alternate routes if possible until the traffic backlog cleared.

While major roads in Calgary were primarily clear by Thursday afternoon, graders were working on large snowdrifts in residential areas in the northwest of the city.

The City of Calgary said two locations remained problematic for the evening rush hour:

• 144th Avenue N.W., west of Symons Valley Road.
• Centre Street North between Stoney Trail and Highway 566.

Motorists also dealt with a road closure at 42nd Avenue S.E. between Ogden Road and Highfield Crescent after a freight train derailed at about 2 p.m.

No one was injured but the road was closed for several hours until the train could be cleared.

Thousands in the dark

High winds and wet snow knocked out power to about 55,000 Calgary homes, with the Country Hills area in the dark for about six hours, said Doris Kaufmann, a spokeswoman with Enmax, Calgary's city-owned utility.

A spring storm brought winter driving conditions back to Coventry Hills in northwest Calgary Thursday. (Submitted by Colin Stang)

Rural electricity provider, Fortis Alberta, said its worst-hit areas were Bassano, Airdrie, Black Diamond and communities south of Lethbridge.

Highway 1 from Calgary to Strathmore saw improved driving conditions but the area east of Strathmore was still a mess because of poor visibility and ice, as well as a jack-knifed semi truck.

More than two dozen flights were cancelled or delayed at the Calgary International Airport.

The weather closed Catholic schools in Airdrie, Chestermere, and Cochrane, but schools in Calgary remained open.

This is the third major snowfall in the Calgary area this month.